midi.c

  1/****************************************************************************
  2
  3   Copyright Echo Digital Audio Corporation (c) 1998 - 2004
  4   All rights reserved
  5   www.echoaudio.com
  6
  7   This file is part of Echo Digital Audio's generic driver library.
  8
  9   Echo Digital Audio's generic driver library is free software;
 10   you can redistribute it and/or modify it under the terms of
 11   the GNU General Public License as published by the Free Software
 12   Foundation.
 13
 14   This program is distributed in the hope that it will be useful,
 15   but WITHOUT ANY WARRANTY; without even the implied warranty of
 16   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 17   GNU General Public License for more details.
 18
 19   You should have received a copy of the GNU General Public License
 20   along with this program; if not, write to the Free Software
 21   Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 22   MA  02111-1307, USA.
 23
 24   *************************************************************************
 25
 26 Translation from C++ and adaptation for use in ALSA-Driver
 27 were made by Giuliano Pochini <pochini@shiny.it>
 28
 29****************************************************************************/
 30
 31
 32/******************************************************************************
 33	MIDI lowlevel code
 34******************************************************************************/
 35
 36/* Start and stop Midi input */
 37static int enable_midi_input(struct echoaudio *chip, char enable)
 38{
 39	dev_dbg(chip->card->dev, "enable_midi_input(%d)\n", enable);
 40
 41	if (wait_handshake(chip))
 42		return -EIO;
 43
 44	if (enable) {
 45		chip->mtc_state = MIDI_IN_STATE_NORMAL;
 46		chip->comm_page->flags |=
 47			cpu_to_le32(DSP_FLAG_MIDI_INPUT);
 48	} else
 49		chip->comm_page->flags &=
 50			~cpu_to_le32(DSP_FLAG_MIDI_INPUT);
 51
 52	clear_handshake(chip);
 53	return send_vector(chip, DSP_VC_UPDATE_FLAGS);
 54}
 55
 56
 57
 58/* Send a buffer full of MIDI data to the DSP
 59Returns how many actually written or < 0 on error */
 60static int write_midi(struct echoaudio *chip, u8 *data, int bytes)
 61{
 62	if (snd_BUG_ON(bytes <= 0 || bytes >= MIDI_OUT_BUFFER_SIZE))
 63		return -EINVAL;
 64
 65	if (wait_handshake(chip))
 66		return -EIO;
 67
 68	/* HF4 indicates that it is safe to write MIDI output data */
 69	if (! (get_dsp_register(chip, CHI32_STATUS_REG) & CHI32_STATUS_REG_HF4))
 70		return 0;
 71
 72	chip->comm_page->midi_output[0] = bytes;
 73	memcpy(&chip->comm_page->midi_output[1], data, bytes);
 74	chip->comm_page->midi_out_free_count = 0;
 75	clear_handshake(chip);
 76	send_vector(chip, DSP_VC_MIDI_WRITE);
 77	dev_dbg(chip->card->dev, "write_midi: %d\n", bytes);
 78	return bytes;
 79}
 80
 81
 82
 83/* Run the state machine for MIDI input data
 84MIDI time code sync isn't supported by this code right now, but you still need
 85this state machine to parse the incoming MIDI data stream.  Every time the DSP
 86sees a 0xF1 byte come in, it adds the DSP sample position to the MIDI data
 87stream. The DSP sample position is represented as a 32 bit unsigned value,
 88with the high 16 bits first, followed by the low 16 bits. Since these aren't
 89real MIDI bytes, the following logic is needed to skip them. */
 90static inline int mtc_process_data(struct echoaudio *chip, short midi_byte)
 91{
 92	switch (chip->mtc_state) {
 93	case MIDI_IN_STATE_NORMAL:
 94		if (midi_byte == 0xF1)
 95			chip->mtc_state = MIDI_IN_STATE_TS_HIGH;
 96		break;
 97	case MIDI_IN_STATE_TS_HIGH:
 98		chip->mtc_state = MIDI_IN_STATE_TS_LOW;
 99		return MIDI_IN_SKIP_DATA;
100		break;
101	case MIDI_IN_STATE_TS_LOW:
102		chip->mtc_state = MIDI_IN_STATE_F1_DATA;
103		return MIDI_IN_SKIP_DATA;
104		break;
105	case MIDI_IN_STATE_F1_DATA:
106		chip->mtc_state = MIDI_IN_STATE_NORMAL;
107		break;
108	}
109	return 0;
110}
111
112
113
114/* This function is called from the IRQ handler and it reads the midi data
115from the DSP's buffer.  It returns the number of bytes received. */
116static int midi_service_irq(struct echoaudio *chip)
117{
118	short int count, midi_byte, i, received;
119
120	/* The count is at index 0, followed by actual data */
121	count = le16_to_cpu(chip->comm_page->midi_input[0]);
122
123	if (snd_BUG_ON(count >= MIDI_IN_BUFFER_SIZE))
124		return 0;
125
126	/* Get the MIDI data from the comm page */
127	received = 0;
128	for (i = 1; i <= count; i++) {
129		/* Get the MIDI byte */
130		midi_byte = le16_to_cpu(chip->comm_page->midi_input[i]);
131
132		/* Parse the incoming MIDI stream. The incoming MIDI data
133		consists of MIDI bytes and timestamps for the MIDI time code
134		0xF1 bytes. mtc_process_data() is a little state machine that
135		parses the stream. If you get MIDI_IN_SKIP_DATA back, then
136		this is a timestamp byte, not a MIDI byte, so don't store it
137		in the MIDI input buffer. */
138		if (mtc_process_data(chip, midi_byte) == MIDI_IN_SKIP_DATA)
139			continue;
140
141		chip->midi_buffer[received++] = (u8)midi_byte;
142	}
143
144	return received;
145}
146
147
148
149
150/******************************************************************************
151	MIDI interface
152******************************************************************************/
153
154static int snd_echo_midi_input_open(struct snd_rawmidi_substream *substream)
155{
156	struct echoaudio *chip = substream->rmidi->private_data;
157
158	chip->midi_in = substream;
159	return 0;
160}
161
162
163
164static void snd_echo_midi_input_trigger(struct snd_rawmidi_substream *substream,
165					int up)
166{
167	struct echoaudio *chip = substream->rmidi->private_data;
168
169	if (up != chip->midi_input_enabled) {
170		guard(spinlock_irq)(&chip->lock);
171		enable_midi_input(chip, up);
172		chip->midi_input_enabled = up;
173	}
174}
175
176
177
178static int snd_echo_midi_input_close(struct snd_rawmidi_substream *substream)
179{
180	struct echoaudio *chip = substream->rmidi->private_data;
181
182	chip->midi_in = NULL;
183	return 0;
184}
185
186
187
188static int snd_echo_midi_output_open(struct snd_rawmidi_substream *substream)
189{
190	struct echoaudio *chip = substream->rmidi->private_data;
191
192	chip->tinuse = 0;
193	chip->midi_full = 0;
194	chip->midi_out = substream;
195	return 0;
196}
197
198
199
200static void snd_echo_midi_output_write(struct timer_list *t)
201{
202	struct echoaudio *chip = timer_container_of(chip, t, timer);
203	int bytes, sent, time;
204	unsigned char buf[MIDI_OUT_BUFFER_SIZE - 1];
205
206	/* No interrupts are involved: we have to check at regular intervals
207	if the card's output buffer has room for new data. */
208	sent = 0;
209	guard(spinlock_irqsave)(&chip->lock);
210	chip->midi_full = 0;
211	if (!snd_rawmidi_transmit_empty(chip->midi_out)) {
212		bytes = snd_rawmidi_transmit_peek(chip->midi_out, buf,
213						  MIDI_OUT_BUFFER_SIZE - 1);
214		dev_dbg(chip->card->dev, "Try to send %d bytes...\n", bytes);
215		sent = write_midi(chip, buf, bytes);
216		if (sent < 0) {
217			dev_err(chip->card->dev,
218				"write_midi() error %d\n", sent);
219			/* retry later */
220			sent = 9000;
221			chip->midi_full = 1;
222		} else if (sent > 0) {
223			dev_dbg(chip->card->dev, "%d bytes sent\n", sent);
224			snd_rawmidi_transmit_ack(chip->midi_out, sent);
225		} else {
226			/* Buffer is full. DSP's internal buffer is 64 (128 ?)
227			bytes long. Let's wait until half of them are sent */
228			dev_dbg(chip->card->dev, "Full\n");
229			sent = 32;
230			chip->midi_full = 1;
231		}
232	}
233
234	/* We restart the timer only if there is some data left to send */
235	if (!snd_rawmidi_transmit_empty(chip->midi_out) && chip->tinuse) {
236		/* The timer will expire slightly after the data has been
237		   sent */
238		time = (sent << 3) / 25 + 1;	/* 8/25=0.32ms to send a byte */
239		mod_timer(&chip->timer, jiffies + (time * HZ + 999) / 1000);
240		dev_dbg(chip->card->dev,
241			"Timer armed(%d)\n", ((time * HZ + 999) / 1000));
242	}
243}
244
245
246
247static void snd_echo_midi_output_trigger(struct snd_rawmidi_substream *substream,
248					 int up)
249{
250	struct echoaudio *chip = substream->rmidi->private_data;
251	bool remove_timer = false;
252
253	dev_dbg(chip->card->dev, "snd_echo_midi_output_trigger(%d)\n", up);
254	scoped_guard(spinlock_irq, &chip->lock) {
255		if (up) {
256			if (!chip->tinuse) {
257				timer_setup(&chip->timer, snd_echo_midi_output_write,
258					    0);
259				chip->tinuse = 1;
260			}
261		} else {
262			if (chip->tinuse) {
263				chip->tinuse = 0;
264				remove_timer = true;
265			}
266		}
267	}
268
269	if (remove_timer) {
270		timer_delete_sync(&chip->timer);
271		dev_dbg(chip->card->dev, "Timer removed\n");
272		return;
273	}
274
275	if (up && !chip->midi_full)
276		snd_echo_midi_output_write(&chip->timer);
277}
278
279
280
281static int snd_echo_midi_output_close(struct snd_rawmidi_substream *substream)
282{
283	struct echoaudio *chip = substream->rmidi->private_data;
284
285	chip->midi_out = NULL;
286	return 0;
287}
288
289
290
291static const struct snd_rawmidi_ops snd_echo_midi_input = {
292	.open = snd_echo_midi_input_open,
293	.close = snd_echo_midi_input_close,
294	.trigger = snd_echo_midi_input_trigger,
295};
296
297static const struct snd_rawmidi_ops snd_echo_midi_output = {
298	.open = snd_echo_midi_output_open,
299	.close = snd_echo_midi_output_close,
300	.trigger = snd_echo_midi_output_trigger,
301};
302
303
304
305/* <--snd_echo_probe() */
306static int snd_echo_midi_create(struct snd_card *card,
307				struct echoaudio *chip)
308{
309	int err;
310
311	err = snd_rawmidi_new(card, card->shortname, 0, 1, 1, &chip->rmidi);
312	if (err < 0)
313		return err;
314
315	strscpy(chip->rmidi->name, card->shortname);
316	chip->rmidi->private_data = chip;
317
318	snd_rawmidi_set_ops(chip->rmidi, SNDRV_RAWMIDI_STREAM_INPUT,
319			    &snd_echo_midi_input);
320	snd_rawmidi_set_ops(chip->rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT,
321			    &snd_echo_midi_output);
322
323	chip->rmidi->info_flags |= SNDRV_RAWMIDI_INFO_OUTPUT |
324		SNDRV_RAWMIDI_INFO_INPUT | SNDRV_RAWMIDI_INFO_DUPLEX;
325	return 0;
326}